Lipids – Part 2 McCafferty. LIPID DIGESTION & ABSORPTION Absorbable forms:
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Transcript of Lipids – Part 2 McCafferty. LIPID DIGESTION & ABSORPTION Absorbable forms:
Lipids – Part 2
McCafferty
LIPID DIGESTION & ABSORPTION
Absorbable forms:
Remember “hydrolysis?”
MouthMechanical: chewing, mixed w/saliva for lubrication
Chemical:
Stomach
Mechanical: peristalsis/churning
____________
Chemical:
For digestion to continue, these fat droplets must be emulsifiedSmall IntestineFat droplets enter small intestinegallbladder contracts and releases __________
synthesized in the ______,
stored in the __________
made from _________
Once fat is emulsified into the liquid, enzymes can work:
Pancreas releases: pancreatic lipase
TG _________________________________(DRAW BELOW:)
Lipid AbsorptionSmall lipid fragments:
Glycerol and Short Chain FAs (SCFAs)Absorbed directly into the bloodstream Portal vein to liver
Lipid AbsorptionBig lipid fragments
Monoglycerides and LCFAs need help! If absorbed into the blood:
They need to be emulsified.
Big lipid fragments, cont.
Enter intestinal cell, re-form TGTG is incorporated into Lipoprotein carriers: Chylomicrons (CM)
Lipoprotein = lipid associated w/proteins
“Shuttle”
Protein and phospholipid act as emulsifiers for the other lipids
Lymph vessel
The tissues can extract what they need from the CMs.
CM remnants
Lipoproteins -- OverviewLipids bound to protein
Spherical structure – “Shuttle”
Classes of LipoproteinsWhat is denser, lipid or protein?
CM chylomicron –
made in intestinal cells
Transports ________TG from ________ to tissues
eg. adipose and muscle
VLDL – very low density lipoprotein
made in liver
Carries TG to tissues
LDL – Made in liverCarries
HDL – Made in liver & intestine
Associated w/ risk for CVD
Recommended LevelsTotal cholesterol
For 30 yrs For 30 yrs (for kids 170 mg/dl)
LDL cholesterol HDL cholesterol Triglycerides (TG) *note controversy surrounding these numbers
LDL to HDL ratioMen: Women:
LDL cholesterol increases with
HDL cholesterol increases with
STORAGE & USE OF FATOverview:
TG is main form of stored E in the bodyAdipose – When body needs fuel
Storing Fat
TG in blood (in CMs and VLDL)(need to get TG into adipose & muscle cells)
INSULIN presentActivates enzyme on blood vessel wall:LPL Lipoprotein LipaseLPL binds w/CM or VLDL and extracts TGBreaks down TG glycerol & 3FAs enter cell
Storing FatIn adipose, TG fat droplets
Storing Fat
In adipose, TG
Adipose cells stretch to hold fat
Once filled to max capacity, cells begin to multiply
Mobilizing Stored Fat
TG in adipose; want to release FAs for E
Activates enzyme inside adipose cellHSL Hormone-sensitive lipase HSL breaks down TG G & FAs
FAs blood Hydrophobic, so bound to protein carrier: albumin cells metabolized for E
USING FAT TO MAKE ATP
•What kind of fat gets used for energy?•What is triglyceride made of?
______________
_____________
_____________
Krebs
ETS
ATP
C-C-C
C-C C-C C-CC-C C-C C-CC-C C-C C-CC-C C-C C-CC-C C-C C-CC-C C-C C-CC-C C-C C-CC-C C-C C-CC-C
Glycerol is converted to pyruvate
can either glucose or acetyl CoA /Krebs/ATP
Fatty Acids (too large to enter Krebs cycle)
can ONLY enter energy metabolism at
Therefore,
So what’s the point?
If we are out of glycogen and need to make glucose for those glucose-dependent tissues, we aren’t going to be able to use fatty acids to do it.
Summary of ATP Production From Fat
Fat is comprised mainly of TG moleculesGlycerol and 3 FAs
Glycerol (3C) enters energy metabolism at pyruvateFAs (broken down to 2C units) enter at acetyl CoAFat can provide a very small amount of glucose form the glycerolComplete oxidation of TG yields ATP, CO2, H2O and body heat.
Cardiovascular Disease
Cardiovascular Disease – general term for diseases of the heart and blood vessels
Coronary Heart Disease (CHD) – AKA Coronary Artery Disease– lack of blood flow to the network of blood vessels surrounding (and serving) the heart.
major cause: atherosclerosis.Atherosclerosis – thickening and hardening of the walls of the blood vessels 2 deposits of fatty material (plaque)
esp. coronary and carotid arteries and abdominal aorta
Heart Attack – Lack of blood flow to the heart muscle resulting in tissue damage and sometimes sudden death
Stroke –blood flow to a part of the brain is cut off
“brain attack.” Usually due to atherosclerosis in the carotid arteries.
Atherosclerosis
Slow, progressive disease which begins in childhood and takes decades to advance.
Coronary arteries are most often affected.
“Response to Injury Theory”Fatty streaks form along arterial wallsProliferation of smooth muscle cells, WBCs and calcium plaques Plaques cause the arteries to lose
elasticity
Thrombosis:
Embolism:
Angina: pain, pressure, and tightness in chest,
back, neck, and arms caused by
Hypertension
The FOUR major risk factors:1. Smoking
HDL, BP, increases platelet stickiness (clots)
2. Hypertension cardiac work, arterial damageRisk :
3. Elevated blood cholesterol major lipid in plaque
4. Lack of regular exercise Sedentary people (60% of US) have double the risk of developing CVD as active people.
Other risk factors include:Heredity – parent or sibling male under 55, woman under 65Gender – male
women post menopause without estrogen
Age Stress and personality type
Type “A” personality, stress, depression
Elevated triglyceridesInversely correlated w/HDL’s
HomocysteineStrong + correlation w/premature diseasewith inadequate B vitamins
(folate, B6 and B12 – fruits and veggies, lean meats)
Also:
ExerciseStrengthens heart muscleLower body fat (also affects diabetes)Better glucose control blood pressure stressExercisers are less likely to be smokersImproved lipid profile (LDL, HDL) blood clotting
Dietary Prevention of Heart Disease
Fat
Saturated fat
Mono vs. Poly
Trans FAs
Sodium
Alcohol
Antioxidants and Phytochemicals
Fiber
Fish
Soy